The invention relates to the technical field of recycling solid organic materials, and more specifically to the recycling of contaminated wood waste, including wood waste treated with CCA (Copper, Chromium, Arsenic), preservatives used in particular for applications such as posts and telephone poles and also for the recycling of the other solid organic materials such as agricultural waste for example.
In the specific application of recycling contaminated wood waste, a process to recycle such wood waste has been developed within the framework of the Applicant's Patent EP 772663. This process referred to as “CHARTHERM” uses adiabatic combustion characterised by the following defined phases.
The treated wood waste is crushed before being introduced into a tall column-shaped tower reactor with a combustion area in its lower part and cooling zone in its upper part. In the lower part of the reactor, the crushed wood is subjected to an adiabatic combustion produced by hot gases having a low oxygen content and a temperature of the order of 400° C., the mass of crushed wood being located above the combustion area absorbing the excess heat carried by the gases, causing gradual cooling down of these gases to a temperature of less than 65° C., thereby creating an inverse temperature gradient and causing condensation which, when it comes into contact with the crushed wood, deposits all the particles, especially metallic particles, tar and steam, which the combustion gases may contain. The non-condensable combustion gases, cleaned of all heavy metals, are removed from the reactor. The oxygen content of the combustion gases introduced into the lower part of the reactor is extremely low in order to prevent ignition of the crushed wood and increase the reduction effect. The charcoal obtained after the adiabatic combustion of the crushed wood includes the reduction of heavy metals and other polluting elements with a view to subsequent recycling in other treatment applications.
The layout of the plant used to perform the “CHARTHERM” process is as follows:
The reactor comprises a column and includes the following items, from the bottom to the top of the column:                a sealed ash hopper equipped with an ash removal system,        a hot gas inlet located in the lower part of the reactor,        a shaking grid making it possible to remove carbonised material and bring about a downward flow of crushed wood due to the effect of vibration,        a gas cooling and filtering zone located above the combustion area,        a sealed crushed wood feed inlet located in the upper part of the reactor,        at the same level as the latter, a combustion gas outlet protected by a grid intended to prevent the ejection of crushed wood and some mechanisms ensuring uniform radial distribution of the crushed wood.        
The actual process itself involves the following phases:                feed crushed material into a column reactor;        adiabatic combustion of said material in the lower part of the reactor resting on a shaking grid with cooling of gases in upper part of reactor;        feed hot gases with low oxygen content into the lower part of reactor and transfer of gases through the reactor column with a gas recycling circuit incorporating a hot air generator, burner, compressor and an interposed device for scrubbing flue gases and recycled gases;        remove treated material in the form of residues from the lower part of the reactor by controlling the shaking grid.        
In practice, the process as described gives satisfactory operational results and produces at the end charcoal ash.
Nevertheless, the Applicant sought to further enhance this process with a quite precise objective, namely obtaining at the end of the process, reduced materials capable of constituting a (secondary) raw material, something which is totally impossible at present. The approach adopted by the Applicant was also intended to increase the usefulness of the plant used to perform the process, thus improving its productivity and profitability still further.